Along with the rapid development of display technology, touch panels have been widely applied in people's life. At present commonly used touch panels are liquid crystal touch panels which mainly comprise a touch structure for achieving touch function and a liquid crystal display (LCD) panel for achieving display function.
The LCD panel includes an array substrate and an opposing substrate (e.g., a color filter (CF) substrate) which are arranged opposite to each other, and a liquid crystal layer disposed between the array substrate and the opposing substrate. An LCD device controls the deflection of liquid crystal molecules by applying voltages to common electrodes and pixel electrodes, and hence controls light transmission. In view of different display modes, the common electrodes and the pixel electrodes may be respectively disposed on the opposing substrate and the array substrate (e.g., twisted nematic (TN) mode), or may be both disposed on the array substrate (e.g., in-plane switching (IPS) mode and advanced super dimension switch (ADS) mode).
The touch panel, for instance, includes an add-on mode touch panel, in which a touch structure and a protective glass sheet on the outside of a display panel are integrated together, and an in-cell touch panel, in which a touch structure is embedded in a display panel. The add-on mode touch panel has the defects such as high manufacturing cost, low light transmittance, thick module, etc. The in-cell touch panel can reduce the overall thickness of a touch module and reduce the manufacturing cost of the touch panel, and hence is favored by various panel manufacturers.
Currently, most touch panels are capacitive touch panels which are divided into touch panels utilizing the mutual-capacitance principle and touch panels utilizing the self-capacitance principle.
As for the touch panel utilizing the mutual-capacitance principle, transverse electrodes and longitudinal electrodes are manufactured on a surface of a substrate, and capacitance will be produced at the intercrossed positions of the transverse electrodes and the longitudinal electrodes. When a screen is touched by a touch object (e.g., a human finger), the coupling of two electrodes near the touch position is affected, so that the capacitance between the two electrodes can be changed, and hence the coordinates of the touch position can be calculated according to the variation of the capacitance.
The touch panel utilizing the self-capacitance principle generally comprises a plurality of self-capacitance electrodes arranged in the same layer and insulated from each other. Each self-capacitance electrode is connected to a touch detection chip through a lead. When a screen is not touched by a touch object (e.g., a human finger), the capacitance of the self-capacitance electrode is at a fixed value; when the screen is touched by the touch object, the capacitance of the self-capacitance electrode corresponding to the touch position is at a value of the fixed value plus the capacitance caused by the touch object, and the coordinates of the touch position can be obtained when the touch detection chip detects the variation of the capacitance value of the self-capacitance electrodes.